A generic optical device embodied as a stereomicroscope is known from DE 102 55 960 A1. The stereomicroscope has a principal objective and a zoom system arranged downstream said objective. Since the zoom system is arranged in a “lying” manner or “horizontally,” i.e. the axis of the zoom system is substantially perpendicular to the optical axis defined by the principal objective, a deflection element is provided between the objective and zoom system to deflect the observation beam path into the corresponding magnification channels of the zoom system. The stereomicroscope further comprises additional optical components, such as filters, shutters, optical splitters, data overlay systems, etc., that are arranged in the observation beam path, said path being directed by further deflection elements into various horizontal planes of the microscope. This construction allows a low-profile microscope to be implemented. At the same time, the deflection elements can be configured as beam splitters, making possible outcoupling of the observation beam path and therefore multiple ports for multiple observers.
The present invention is not limited to the aforesaid construction according to DE 102 55 960 A1, but can be implemented in the context of any optical device in which a deflection element is present (or can be provided) for deflection of the beam path. The goal of the invention is to compensate for vibrations occurring in such an optical device, the term “vibrations” being intended generally to denote unintentional oscillations, motions, or other displacements out of the rest position. Such vibrations can be triggered by the user of the optical device him- or herself or by vibrations of the mounts supporting the optical device (e.g. the stand of a microscope), or can be transferred from walls, ceilings, or floors that are connected to the optical device (e.g. ceiling mounts or floor stands).
A damping system for a microscope is known from US 2001/0024 320 A1, in which a dynamic vibration absorber is provided which is mounted, for example, at the connecting point between the microscope and microscope stand. The dynamic vibration absorber can be a structure containing a piezoactuator. A vibration sensor senses vibrations of the stand arm to which the microscope is attached, whereupon a control system causes oscillations of the piezoelectric actuator in the Z direction (parallel to the optical axis) in such a way that the vibrations of the stand arm are very largely eliminated. The microscope tube and a CCD camera are arranged above the vibration absorber. Instead of a piezoelectric actuator, a passive damping element (silicone plastic or urethane plastic) can also be used. In further embodiments, vibration absorbers are provided at further locations in a microscope system made up of a microscope, stand, illumination unit, and imaging unit. The proposed arrangements are intended to prevent oscillations of the stand arm in the Z direction from being transferred to the microscope, so that the latter remains at rest. Unsharpness in the observed image due to vibration is thereby very largely eliminated.
DE 103 06 440 A1 describes an apparatus for suppressing vibrations in all three spatial directions for a microscope mounted on a stand. An actively reactive flexible structure (ARES) component is arranged, as a vibration compensation device, in, on, or instead of, a part of the microscope or stand. An ARES unit is a self-regulating component that, based on measurement of vibrations, applies control to integrated drive elements in such a way that they counteract the vibration in real time so that the vibration does not result in a change in position of the external contours. In this context, the ARES component can directly replace the support arm (stand arm), i.e. can serve simultaneously as a supporting and vibration-compensating element.
DE 43 42 538 A1 is likewise based on the object of decoupling a surgical microscope from forces acting on the stand that are transferred to the surgical microscope. For this purpose, it is proposed to mount at least one drive element for compensating for vibrations in or on the microscope, an electronic circuit being present that converts the signal of a sensor into the signal for the drive element. Linear motors are used as drive elements. It is advantageous in this context to arrange two linear motors in such a way that a slight movement of the microscope objective in one plane (X and Y directions) can occur. The principal objective is then moved in the X-Y plane in opposite-phase fashion to the external deflection, thereby improving image quality. The aforesaid document discloses various arrangements of such force-exerting devices for vibration decoupling of a surgical microscope, only vibrations in the aforesaid X-Y plane being compensated for. Similar devices for vibration decoupling of an optical device or microscope are described in U.S. Pat. No. 5,786,936 and in U.S. Pat. No. 5,731,896.
A feature common to the aforementioned existing art is that vibrations caused by the user's operations, or by other external vibrations transferred to the stand or microscope, are decoupled from the microscope by providing, at a suitable location on the microscope structure, a device that generates opposite-phase vibrations which eliminate the external vibrations. A disadvantage of this mechanical stabilization or decoupling of the microscope is the need for a separate component for vibration damping. The use of relatively large and heavy (linear) motors for adjustment and counter-control of the optical components requires very accurate control, and cannot achieve stabilization in the Z direction (parallel to the optical axis). When piezoelements are used in accordance with the aforesaid US 2001/0024320 A1, on the other hand, only vibrations in the Z direction are compensated for. The use of the aforesaid ARES components according to DE 103 06 440 A1, in contrast, has the advantage of vibration compensation in all three spatial directions. A further disadvantage of the known vibration compensation system is the system-inherent inertia of the vibration dampers that are used; this must be taken into account in the vibration compensation control system and results in a corresponding large outlay for control technology.